Adenomatous Polyposis of the Colon

Background and History: 

This syndrome has been known since the middle of the 20th century and consists of several variants.  It is significant as an important cause of colon cancer but also increases the risk of other familial cancers. 

Clinical Correlations: 

Individuals with this disease (sometimes called Familial Adenomatous Polyposis or FAP) develop numerous growths known as polyps in the gastrointestinal tract, primarily in the colon.  They often appear by the age of 16 years and many of these become cancerous with the mean age of onset of colon cancer being 39 years.  Other tumors often develop as well, including those in the liver, soft tissue, thyroid, and adrenal glands.  Dental anomalies such as crooked teeth, missing teeth, and cysts in the jaw occur in some families.

Asymptomatic but characteristic pigmentary changes are seen in the retina of the eye in the majority of individuals.  These are highly suggestive markers for this disease but are not present in all patients and may be seen in unaffected individuals.


FAP is an autosomal dominant condition in which the manifestations are passed from affected parents to each child with a 50% probability.  Since virtually all individuals with the causative mutations will eventually develop cancer if untreated, it is important that at risk relatives are tested for the presence of the APC mutation.

Diagnosis and Prognosis: 

The extremely high risk of cancer mandates lifelong surveillance, especially of the gastrointestinal tract.  The only effective treatment is removal of the colon before the polyps become malignant.  Treatment with nonsteroidal anti-inflammatory drugs such as sulindac can reduce the number of polyps but does not prevent cancerous changes in those remaining.

The pigmented lesions in the eye should be periodically evaluated since they rarely develop cancers as well.  They do not cause symptoms but their presence is an important marker for FAP and, since they are present at birth, can enable an eye doctor to identify individuals at risk.

Additional Information